In September, a doctor named John Zhang announced that a baby, created via a complicated fertility treatment involving DNA contributions from three people, was successfully delivered the previous April. Now the U.K. has opened the way for more attempts at creating babies with three parents.

The fertility treatment involves sperm, an egg from the prospective mother, and an egg from a donor and has been used to help women who have mitochondrial issues with their eggs, replacing the nucleus DNA of those eggs with that of donor, either before or after fertilization. The embryo then carries the donor’s mitochondrial DNA, which amounts to less than 1% of the resulting child’s genes. CBS News reports that on Thursday, Britain’s fertility regulator, Human Fertilisation and Embryology Authority, approved the technique.

The regulator’s chair, Sally Chesire, said in a statement, “Parents at very high risk of having a child with a life-threatening mitochondrial disease may soon have the chance of a healthy, genetically related child.” Mitochondrial issues can result in muscular dystrophy, muscle weakness and organ failure.

Advertisement

Anyone who wishes to attempt fertility treatment using the 3-parent method must apply on a case-by-case basis via a clinic to HFEA. According to the BBC, the Newcastle-upon-Tyne Hospitals NHS Foundation Trust and Newcastle University is first in line to grab a license and are aiming to help 25 women a year. Professor Frances Flinter of the NHS Foundation Trust told the BBC, “It is infinitely preferable that the early clinical trials should be done in a tightly regulated system in the UK, with long term follow-up of any children born, rather than in countries where there is no regulation or oversight.”

The decision does have it’s detractors. In addition to anti-abortion groups fearing the procedure will lead to discarded fertilized embryos, some fear this is the first step towards “designer babies.” The BBC quotes Dr David King, who works for advocacy group, Human Genetics Alert, as saying, “Already, bioethicists have started to argue that allowing mitochondrial replacement means that there is no logical basis for resisting GM babies, which is exactly how slippery slopes work.”